need help with vistaprint

Does anyone know how i can change the size of a picture so that I can upload it to use for save the date magnets?
My FH is the computer wiz, not me and he's not around.

i ad a problem with uploading....are you using netscape....if so, vistaprint doesnt work with it.....you need to go on aol or internet explorer


hope this helps....trust me i know how fustrating it is